In order to improve the chemical and mechanical properties of a substrate, e.g., hardness, wear resistance, corrosion resistance, and fatigue resistance, plating of the substrate with a metal and thereafter forming a nitride region on the plated substrate are generally practiced. However, most of these processes produce a thick coating over the surface of the substrate and do not penetrate into the substrate. This results in a rough substrate surface as well as significant brittleness because of byproduct growth or hillocks that are formed. Utilizing these processes on a razor blade does not actually increase the strength of the razor blade, but instead produces a brittle cutting edge. If the cutting edge breaks on a razor blade, the remaining razor blade will yield an extremely uncomfortable shave.
There is a need for an improved coated razor blade and method for coating the razor blade that overcomes these shortcomings. Accordingly, the present invention advantageously allows for the type, composition, and thickness of a first material to be easily changed and controlled, which strengthens the underlying razor blade and reduces its brittleness. The methods disclosed herein will greatly reduce or eliminate the severe roughening and/or byproduct growth on the surface of the razor blade. In addition, these methods permit the nitriding to be localized in a particular area or throughout the razor blade. In turn, these methods also provide a more controlled and deeper nitriding of the razor blade, both vertically and laterally, as well as a more gradual nitriding gradient, thereby resulting in a razor blade with a smooth cutting edge that exhibits increased hardness, strength, and durability.